巨型矿床形成的元素分异机制  

Elemental differentiation mechanism for giant ore-deposits

作　　者：张涛[1] 赵博[2,3] 张德会[1] 王斌[1] 刘源[1] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]长安大学地质工程与测绘学院,西安710064 [3]长安大学地质资源与地质工程博士后科研流动站,西安710064

出　　处：《世界地质》2015年第3期639-645,共7页World Geology

基　　金：国土资源部公益性行业科研专项基金(201411024);国家自然科学基金(41373048)联合资助

摘　　要：基于"大多数矿石形成过程源于壳幔分异作用扩大"之认识,探讨了从地幔到地壳、从(上)地壳再到矿石堆积过程中的元素比值变化,发现元素在这两个过程中的分异趋势并不同步。壳幔分异使(上)地壳成为大部分矿石和矿胎的储库,即大多数不相容元素强烈分配进入地壳,相应的元素比值(相容性)与巨型矿床堆积吨位指数(TAI)之间表现出一定的线性相关程度。岩浆-热液矿床在地壳中的形成则依赖于浓集系数(矿石品位与克拉克值之比),后者与元素相容性之间的差异显著,反映成矿作用较之于成岩作用(即壳幔分异)更为复杂,浓集系数与TAI之间亦为线性相关。总之,元素形成巨型矿床的能力不仅与其克拉克值有关,还会受到元素地球化学行为、尤其是其在地球演化各个阶段的分异行为的制约。Based on the knowledge that most of the ore-forming process stemming from an expansion of the fractionation from mantle to crust,the abundance ratios for ore-forming elements,from mantle to crust and then to ore accumulation are discussed. The authors discovered that the elemental differentiation behaviors were not completely accordant during the two processes. After the crust-mantle differentiation,the（ upper） crust acted as a reservoir for most ores and protore beds. In other words,most of the incompatible elements were strongly distributed into the crust. There is a clear linear correlation between abundance ratios（ elemental compatibility） versus the tonnage accumulation index（ TAI） for giant deposits in this differentiation process. Magmatic-hydrothermal deposits formed in the earth＇s crust depending on its concentration coefficient（ the ratio of ore grade to its Clark）. A clear linear relationship exists between element compatibility and its concentration coefficient as well,but there are significant differences between element compatibility and its concentration coefficient counterpart,showing that metal-logenesis is much more complicated than diagenesis（ namely crust-mantle differentiation）. In short,the ability forming giant ore deposit for elements may not only associate with its Clarke values,but also with its significantly different geochemical behaviors,especially the fractionation behaviors in various stages through earth evolution.

关 键 词：巨型矿床 相容性 浓集系数 累积堆积吨位指数 

分 类 号：P612[天文地球—矿床学]